1. Field of the Invention
The present invention relates to a mobile communication terminal, and more particularly to a mobile communication terminal for indicating a low-voltage state of its own battery and a method for warning a user of the low-voltage state of the mobile communication terminal.
2. Description of the Related Art
FIG. 1 is a flow chart illustrating a method for warning a user of a low-voltage state of a conventional mobile communication terminal. Referring to FIG. 1, a mobile communication terminal checks a power-supply voltage of a battery at step 100, and determines at step 101 whether the battery is reduced to a power-supply cut-off voltage level. If it is determined at step 101 that the battery is not reduced to a power-supply cut-off voltage level, the mobile communication terminal determines at step 102 whether the battery is reduced to a low-voltage state. If a low-voltage state is found, a user of the mobile communication terminal cannot establish a call connection state with a called party, though the user can perform simple operations such as a phone number search on the mobile communication terminal. However, if the battery is reduced to a power-supply cut-off voltage level, the user cannot search for a desired phone number on his or her mobile communication terminal. If it is determined at step 102 that the mobile communication terminal is in a low-voltage state, it is determined at step 103 whether the mobile communication terminal is communicating with a terminal of a called party. Different display intervals of an alarm message are set up depending on the determination result at step 103. If the mobile communication terminal is communicating a called party, a warning timer is driven in a call connection state at step 104, and an information screen indicating the low-voltage state of the battery is displayed on a display of the mobile communication terminal while a speaker outputs an alarm sound at step 105. Then, if the battery reaches a power-supply cut-off voltage, the mobile communication terminal is powered off. However, if the mobile communication terminal is not communicating with a called party, a warning timer is driven in a wait mode at step 106, and an information screen indicating the low-voltage state of the battery is displayed on a display of the mobile communication terminal while a speaker outputs an alarm sound at step 107. A conventional mobile communication terminal consumes ten times more power in the call connection mode than in the wait mode, and therefore in a call connection mode it uses a warning timer to warn of a short time remaining in operation. The mobile communication terminal is then compulsorily powered off after the lapse of a predetermined time.
If the battery is reduced to a power-supply cut-off voltage level at step 101, the mobile communication terminal determines whether a power-supply cut-off flag is set up at step 108. The power-supply cut-off flag indicates that a voltage level of the mobile communication terminal has reached a power-supply cut-off voltage level. If it is determined at step 108 that the power-supply cut-off flag is set, a timer for powering off the mobile communication terminal is driven. Therefore, the mobile communication terminal stops communicating with the called party after the lapse of a predetermined time at step 109, and is then powered off at step 110. However, if the voltage supplied to the mobile communication terminal is determined to be the power-supply cut-off voltage level at step 101, and the power-supply cut-off flag is determined to not be set at step 108, then the power-supply cut-off flag is set at step 111, and a timer for powering off the mobile communication terminal is driven at step 112.
In this way, the conventional mobile communication terminal drives a timer for a predetermined time after sensing a low-voltage state of the battery, and outputs an alarm sound indicating the low-voltage state at predetermined intervals. The mobile communication terminal is then powered off after the lapse of the predetermined time.
Conventional mobile communication terminals enable a user, i.e. caller, to recognize an alarm sound signaling a low-voltage state, but are unable to allow a called party to recognize the alarm sound signaling a low-voltage state. The called party is then unable to recognize the reason for the call termination; specifically, the called party cannot recognize whether the caller intentionally powered off the mobile communication terminal or whether the battery in the caller's mobile communication terminal is consumed. This remains the case even if the called party receives information indicating a power-off state of the caller's mobile communication terminal. As a result, the called party may continuously attempt to establish a call connection state with the caller. Further, if the caller does not carry a spare battery, he or she cannot inform the called party of this situation.